This invention relates to bearing closure assemblies, and, in particular, to bearing closure assemblies for dynamoelectric machines (e.g. fractional horsepower electric motors). While the invention is described with particular emphasis to its dynamoelectric machine application, those skilled in the art will recognize the wider applicability of the inventive principles discussed hereinafter.
Certain dyanmoelectric machines are exposed in applicational use to environments having contaminants adverse to machine life. For example, motors used to drive the tumbling basket of a clothes dryer are subjected to heavy airborne lint environmental contamination. Unless some protective measures are taken, the lint enters the bearing structure of the motor and draws lubricant from the bearing, which eventually results in bearing failure and motor loss.
A number of arrangements are known in the prior art which attempt to solve the bearing contamination problem. One common solution in the prior art was to incorporate a separate lint shield or seal which was mounted about the motor shaft with very close tolerances. The lint shield presents a physical barrier to entrance of the contaminants. For example, it has been known to use flexible molded fittings which essentially ride along the motor shaft to create the lint barrier. While this approach works for its intended purpose, the use of this form of lint shield requires very close control of both lint shield dimension and shaft concentricity in order to maintain the proper spacing between the shield and shaft. When close control is not maintained and permitted to exceed tolerance, for example, bearing seal integrity is lost. Further, poor shaft concentricity may cause the shield to ride on the motor shaft resulting in undesirable noise generation.
Surprisingly, the invention disclosed hereinafter permits increased tolerances and dimensions between the shaft and the lint sealing structure, thereby lowering product cost, while providing an improved lint barrier for the bearing structure. The clearance between the closure and shaft can be increased because the axial dimension of a flange defining the shaft passage is much larger than previous designs. I have found this increased distance in itself offers protection against bearing contamination. In addition, a conventional oil slinger is positioned adjacent the bearing closure, which helps to define a baffle structure for contaminant flow. The baffle structure and flange dimension are such that even if lint, or other air borne contaminants, begins to enter the baffle area, it becomes trapped in the passage. The lint or other contaminants thereafter block further contaminant flow long before any of the air borne contaminants reach the area of the bearing. The design thus makes use of the contaminants themselves, a cause of bearing failure in the past, to prevent bearing failure.
In other motor applications, it is highly desirale to prevent water from entering the wick-lubrication system of the motor as the water will deplete the lubricant and will cause premature bearing failure.
During the prosecution of the above-noted prior U.S. application Ser. No. 887,947, the following prior art U.S. Pat. Nos. 1,677,936, 3,343,016, 3,846,652 and 3,855,489 were cited.
In one embodiment of this invention, the bearing closure also is utilized as a keeper for a hub ring. The hub ring is a conventional structure which permits the motor to be mounted in its intended application.
One of the objects of this invention is to provide an improved bearing closure means.
Another object of this invention is to provide a bearing closure having an enlarged axial dimension structure passing an associated shaft, the enlarged axial dimension permitting increased radial tolerances between the shaft and the enlarged axial dimension structure.
Another object of this invention is to provide a bearing closure which may be press fit within a hub of an end shield structure for a dynamoelectric machine.
Another object of this invention is to provide a bearing closure which effectively repels or inhibits water from entering the wick lubrication system of the motor and yet, surprisingly, does not require close radial tolerances or seals between the bearing closure and the shaft.
Still another object of this invention is to provide a bearing closure which results in a long service life for the motor and yet which is of simple and economical construction and which is easily and rapidly installed.
Other objects of this invention will be apparent to those skilled in the art in light of the following description and accompanying drawings.